Mullet industry seeks sustainable operation: Luo Xiuwan and Li Wuzhong after the Fisheries Agency's estrogen ban

By Luo Hsiu-wan (retired teacher, Institute of Fisheries Science, National Taiwan University) and Li Wu-chung (agricultural economist)

Before the Lunar New Year, the use of estrogen in farmed grey mullet roe drew public concern, with operators and officials blaming each other, yet it was peculiar how rarely academics came forward to express an opinion. The responses from the Fisheries Agency and the Ministry of Health and Welfare were not clear enough, leaving consumers and grey mullet farmers at a loss. The storm now appears to have subsided somewhat, but many questions remain unresolved, and the competent authorities should step forward to explain and follow up.

Drug use in farmed food fish treats not only the fish but also creates food safety risks for consumers

In fact, Taiwan's aquaculture industry has always had a clear set of regulations and evaluation standards, but they have not been enforced or effectively monitored and managed, which is why today's ambiguous arguments have emerged. In recent years, as people's awareness of food safety has awakened, the drugs used in farmed food fish may affect consumer health, drawing wide public concern. The competent authorities should adopt a professional and responsible attitude, grasp public sentiment, effectively guide and manage operators and related industries, and strictly abide by the regulations, so that Taiwan's aquaculture can develop sustainably and make a greater contribution to Taiwan's food security and fishing village economy.

Drugs are both a life-saving elixir and a poison. Given that drugs have a far-reaching impact on food safety, and that a growing body of evidence shows that hormone abuse brings a high risk of cancer to the human body, under the current regulations on aquaculture drug use, permitted drugs are all listed on a positive list; any drug not included is prohibited.

Japan's aquaculture drug regulations further specify that drugs for industrial use, food additive use, and reagent use may not be used in the aquaculture industry. And we know that estrogen cannot be used in ordinary foods or cosmetics, because exogenous estrogen affects both fish (as food) and humans (as consumers), and even a minute amount of estrogen (pg to ng/ml) will have an effect, so its use requires great caution.

Estrogen acts broadly within organisms; no problem is not the same as undetectable

Estrogen, whether exogenous or endogenous, must bind to its specific receptors in an organism to set off a series of physiological effects, and estrogen receptors are mostly located in the brain, gonads, liver, muscles and bones, various internal organs, and the immune system, so the scope of its influence is quite broad; besides acting on the reproductive system, it also acts on and affects other organs. Administered hormones are excreted from the fish's body after acting on the reproductive-related systems and other sites with receptors, so testing happens after the effect has already occurred; whether it can be detected is no longer the key point. The key point is that hormones must not be administered. After all, safety does not rely on testing alone; it should return to the traditional farming method that does not use hormones.

Domestic research has also pointed out that estrogen may, through estrogen receptor alpha and other cellular signaling pathways, alter the expression of the GnRH gene and interfere with the development of fish embryos (Kang Chih-wei, 2011). Therefore, exogenous estrogen must not be added at will, let alone used in food. However, hormones and certain reagents may be used to treat or breed broodstock, but adult fish treated with such drugs and their fertilized or unfertilized eggs must not be used as food. Taiwan is an advanced country, and the management of drug use at aquaculture food-fish farms and seed and seedling breeding farms should be clearly distinguished, regulated, and monitored, not lumped together.

The competent authorities should track the health status of grey mullet consumers

Because estrogen has been used in domestic grey mullet farming for more than ten years to raise the proportion of female fish and increase the amount of grey mullet roe, and although no direct cases of harm have been heard of, based on risk control, the Fisheries Agency and the Department of Health should work together to conduct longer-term follow-up testing on consumers who prefer eating grey mullet roe and grey mullet rice noodles, so as to truly understand whether it has caused any adverse effects on the human body.

Since the Fisheries Agency has already announced a ban on feeding farmed grey mullet with feed containing added estrogen, it surely has its basis, and it claims it will begin sampling and testing feed starting in 2017; it should thoroughly investigate the types and doses added by feed manufacturers, so that biological experts can then be commissioned to conduct experiments to understand whether there are adverse effects on fish and humans.

After the ban, the government should study supporting measures to minimize operators' losses

For the 1- to 3-year-old farmed grey mullet still in ponds, since estrogen has already been used, if under current regulations they cannot be used as food, the Fisheries Agency should have supporting measures for how to handle them so that farmers' losses can be reduced to a minimum. We suggest that for pond-farmed grey mullet that had already been given estrogen before the ban, taking into account farmers' livelihoods and consumers' rights, operators may return to traditional farming methods until they are ready for market, but we suggest the government could follow the example of genetically modified soybean food and specially permit operators, within this year and next, to use "product traceability labeling" to indicate the pre-ban usage (including the type and dose of estrogen used, the dates and period of use, etc.), and to indicate that estrogen has indeed not been used since the ban; once the government has verified this clearly, the fish may be sold on the market.

Given that estrogen acts in both fish and the human body, involving not only reproduction and the endocrine system but also physiology such as immunity, the government should invite relevant scholars and experts to conduct in-depth discussion. At the same time, to remove unnecessary food safety risks, banning hormones is not just about being undetectable; more importantly, no hormones may be used throughout the entire farming process if the fish are to be used as food fish. This concerns food safety and the sustainable operation of the aquaculture industry and must not be deliberately blurred.

Should Taiwan's aquaculture industry follow the European Union and completely ban estrogen?

The use of sex hormones in aquaculture was indeed an important technology for boosting industry profits in the early days. Old aquaculture textbooks state that using sex steroids during the sensitive stage of sex differentiation, from one week to one month after hatching, in some freshwater fry and tilapia fry, can regulate the sex ratio (%) of pond fish, so when breeding and farming encounter large differences in growth rates between males and females, operators would consider this strategy.

As consumers' food safety awareness has risen, many European countries have explicitly prohibited the use of hormones in farmed food fish (European Directive 96/22/CE). But the authorities in Taiwan and Japan seem to still take a tacitly permissive stance. In Japan, no official information on this is seen, but in the book "Japan's Aquaculture" (Nakada Makoto, Sai Shobo, 2008), the author also frankly states that Japanese aquaculture operators use hormones to regulate the sex of fry and that there are food safety concerns; Professor Nakada believes it is necessary to clarify this.

The sex differentiation period of aquaculture fish species is mostly concentrated from the end of the egg hatching stage to within one month after hatching. At this stage the fish are very small, so the total dose used should be relatively small. But in the case of Japanese eel and grey mullet, their sex differentiation period comes later; Japanese eel must reach 15 to 20 cm and grey mullet 5 to 7 cm for hormone treatment to be relatively effective, but at this stage the fish are already not small, and the amount of hormone used is much greater, so by food safety standards they can no longer be farmed as food fish.

Therefore, at this moment, we perhaps need not "completely" prohibit the use of hormones for sex regulation in farmed fish as European Union countries do, but before research is clear, we could perhaps temporarily allow it only for regulating the sex of fish species whose sex differentiation occurs within one month after hatching, while all food fish brought to market must indicate via product traceability labeling whether hormones were used, and farmed fish not treated with hormones should also clearly state that no hormones were used. As for the farming of food fish such as Japanese eel and grey mullet, whose sex differentiation period comes relatively late, use should be prohibited following the EU model.

As for whether the recommendation to temporarily allow estrogen use in farmed fish species with early sex differentiation violates the bottom line of food safety, aquaculture scholars and experts in Taiwan and Japan might jointly explore: how can the food safety of such aquaculture fish be maintained? This would respond to possible future development trends and safeguard the stable development of the domestic aquaculture industry.

What should operators do after the ban? The authorities should provide substantive guidance and also explain clearly to consumers

As the new farming season begins, it is again the critical period for putting feed into grey mullet ponds. After the competent authorities issued the ban, they should further invite scholars and experts to meet together to discuss supporting guidance measures and teach operators what to do. The authorities should also step forward to explain clearly to consumers, so as to reduce people's doubts about the food safety of grey mullet. Grey mullet is an important migratory wild fish and farmed fish species in Taiwan, bringing considerable wealth to fishermen every year, and how to keep this industry sustainable is a very important issue for the aquaculture sector.

And "crisis is an opportunity." The Fisheries Agency of the Council of Agriculture, Executive Yuan, the Fisheries Research Institute, operators, and the industry-government-academia units involved in aquaculture research should take this opportunity to pool ideas and jointly study and discuss grey mullet farming methods that meet food safety standards, so that the grey mullet farming industry can be sustainable. Consumers can also eat delicious grey mullet feasts and grey mullet roe with peace of mind, which will further help the export of grey mullet roe.